Syria’s opposition struggled to overcome deep rifts on Thursday and form a united front for a proposed international conference to try to end the Syrian civil war.

Delegates at inconclusive talks in Istanbul agreed to add 14 named members of a liberal bloc led by veteran figure Michel Kilo to the 60-member assembly of the Syrian National Coalition, the closest body that President Bashar al-Assad’s foes have to an overall civilian leadership in the two-year-old uprising.

The coalition also agreed in principle to admit another 14 members of activists’ groups from inside Syria and 15 members linked to the Free Syrian Army, an umbrella organization for anti-Assad fighters.

But a neutral mechanism to choose these 29 new members has not been agreed and another battle to name them is shaping up for the next coalition meeting on June 12, members said.

Acting coalition head George Sabra said the group had agreed on a “plan for the transitional period,” but did not elaborate.

The group had also set up agricultural, education and health committees to try and mitigate the humanitarian crisis in Syria, he added.

The coalition has already said it will not take part in a U.S.-Russian peace initiative, dubbed Geneva 2, so long as key allies of the Assad regime, Iran and Lebanese Shiite movement Hezbollah, are waging war alongside government forces.

Despite a marked diplomatic presence at the hotel hosting the Coalition’s meeting, Sabra denied the group had been pressured into taking any decisions.

“No one can pressure us. Bashar al-Assad and [his father and predecessor] Hafez al-Assad before him, in their ugly dictatorships, were unable to pressure us,” Sabra said.

“The Syrian revolution... does not accept any pressure,” he added.

International powers fear that unless deep fissures in the opposition ranks are healed, the chances of a successful Geneva peace conference happening soon are slight.

But many hurdles remain in the process to choose new leaders for a coalition that has been rudderless since March and to name a provisional government that could strengthen what are now weak links with rebel units inside Syria.

Sabra said agreeing the names of the new members required “long deliberations” because they represented “quality not quantity.”

Sounding optimistic, Sabra said: “The coalition has succeeded in undergoing the expansion.” He added that choosing a new coalition president has been postponed at least until June12.

Undercut Russia

Hours before the announcement, a U.S. State Department spokeswoman said Washington was “hopeful that the opposition will vote to elect leadership and to come to a conclusion on how they will expand their membership.”

“We... expect when they make their final decisions we will be able to work with those leadership members and move forward in planning the Geneva conference,” she said.

Kamal al-Labwani, a maverick member of the coalition, said a rapprochement between the liberal and Islamist wings of the opposition could help it undercut Russian attempts to have figures among the representatives of the opposition at Geneva who are willing to allow Assad to stay in power.

“It is very dangerous to allow an opposition delegation to go to Geneva without sticking to the goals of the revolution, or accept an early ceasefire under the excuse that the people a retired, without guarantees that the regime will depart,” Labwani said.

“An incomplete peace that awards a de facto pardon to Bashar and his cohorts will be far more costly than a continuation of the war.”